Apart from the ability to see well, the lasting impression that many patients will take away from the practice is the fit and comfort of their spectacles.
No matter how much or little is paid for your products and services, how well the practice is presented, the efficiency and friendliness of the staff, the standard of the equipment and professionalism of the eye examination, if the patient’s spectacles do not fit correctly or are not comfortable to wear, all the foregoing will soon be forgotten. Any discomfort caused by ill-fitting glasses generates a constant negative reminder of your practice.
As a consequence, the final fitting and comfort of your patient’s spectacles should be treated with the utmost importance at the time of collection. Poorly adjusted frames not only cause much irritation to the patient but also impact on the optical performance of the lenses, particularly in the case of multifocals and high prescriptions. It is vital therefore that great care is taken both before and at the time of collection, to ensure the patient leaves the practice with spectacles that have been made correctly, checked for accuracy and are comfortable and adjusted to fit perfectly. This is, in effect, your last chance to get it right first time.
Of course, the whole process starts with the initial dispensing and ensuring that the frame chosen by the patient is suitable and fit for purpose. Then, if the job is to be done ‘properly’, measurements must be taken and recorded to ensure the frame can be set up correctly prior to collection. This will minimise the amount of time and adjustment required by the dispenser when the patient calls to collect.
To achieve this, you will need some basic equipment at your disposal:
Optical rule, temple width calliper, pantoscopic tilt measuring gauge, face form measuring gauge, corneal vertex distance measuring gauge, frame alignment gauge.
As a minimum, I would suggest the following measurements are taken in every case:
- Eye size.
- Bridge size.
- Side length to bend.
- Head width at the ear point
In addition, you could also record:
- Pantoscopic tilt (joint angle), face form (dihedral) angle and corneal vertex distance (CVD). These measurements will be required if the patient is being fitted with individualised lenses.
However, if multifocal or individualised lenses are to be supplied, the frame to be used should be adjusted and fitted before any lens measurements are taken or digital devices are used to calculate optical centres and compensated lens powers. See paragraph on methodology of adjustment below.
Verification and pre-delivery inspection
When the completed spectacles are ready, it is normal procedure, before advising the patient that their new glasses are ready for collection, to check that the lenses conform to the prescription issued by the optometrist and that the optical centres, bifocal segment or progressive/degressive heights are set correctly. However, in addition to this, the spectacles should also be given a full ‘pre-delivery’ inspection (in much the same way that a garage gives a new car a full inspection and preparation prior to handing over to the customer).
This would include inspecting the lenses and frames for scratches and blemishes, checking all frame screws are fully tightened, especially the rim screws on metal frames, oiling the side joints and then ‘setting up the frame’ to conform to the measurements taken at the time of dispensing. Finally the frame and lenses must be spotlessly clean before putting them into a well-fitting case along with a neatly folded lens cloth together with any frame or lens warranty cards. This will, of course, take a few minutes to do but the extra effort will be well rewarded when you come to hand over, what for many people is a very personal and costly item which they will only purchase once every two or three (or more) years.
The job of setting up spectacle frames is often done ‘by eye’ but is achieved more accurately using a frame alignment gauge. The ‘Frame Aligner’* is such a gauge which has been designed by the author (see figure 1) and enables you to ensure the frame is symmetrically aligned and that the head width and side lengths are set correctly. It can also be used to check optical centres, bifocal segment heights and progressive/degressive lens markings.
Figure 1: The Frame Aligner
You will also need some optical tools and accessories. The following list is by no means exhaustive and everyone will have their own favourites. However, a basic set would include:
- Frame heater with adjustable heat settings.
- Screwdriver with 1.5mm and 2.2mm flat head.
- Screwdriver with 1.5mm and 2.0mm cross head.
- Side bending pliers (or a good thumb with a short nail).
- Cutting plier (hard metal capacity).
- Pad adjusting plier (slim, long nose).
- Inclination plier (one 7mm nylon jaw & one round metal jaw).
- Flat holding plier (with two 7mm wide nylon jaws).
- Wide angle angling plier.
It is also useful to have:
- A hand file.
- A set of needle files.
- Emery paper.
- Self-closing screw holding tweezers.
- Push-on nose pad removal tweezers or pliers.
- A pin point oiler.
- Thread lock.
- A micro flame torch.
- A variable speed hand drill and accessories.
If you are glazing or fitting remote edged lenses at the practice, you will also need:
- Nylon rim shaper pliers.
- Lens alignment pliers.
- Supra mounting ribbon.
- Rimless compression mount pliers, staple cutters and extractors.
Methodology of Adjustment
There is a lot more to frame adjustment than ‘a bit of bending’. Here I describe a methodology of adjustment I have devised which involves four basic stages to follow when adjusting a frame to achieve a good fit. These can be memorised with the mnemonic word ‘HELP’.
H is for Head Width
Before doing anything else, it is important to get the head width of the frame right. The distance between the fully opened sides at the bends should correspond to the patients measured head width at the ears. If the head width of the frame is too narrow and fixed hinges are fitted to the sides, it will have the effect of pushing the front forwards and may cause ‘tram lines’ along the side of the patient’s head. If spring hinges are fitted, it will cause the spring to be constantly under strain and may result in early failure of the hinge. Naturally, this does not apply with Beta-Titanium flexible sides fitted to some rimless frames.
In some cases, particularly with heavier lenses or if the patient finds that the spectacles are prone to slipping on the nose, the head width of the frame may be set approximately 5mm less than the actual head width in order to provide a small degree of pressure at the ear points.
Figure 2: Adjusting the angle of let back
The correct head width is achieved by adjusting the ‘angle of let back’ (see figure 2). It is important that the sides are let back at equal angles (unless the shape of the patient’s head dictates otherwise) to ensure the frame sits symmetrically on the face of the patient. This is easily and accurately checked on the frame aligner gauge (see figure 3).
Figure 3: Checking symmetry with a frame aligner gauge
E is for Ears
The next job is to adjust the length to bend of the sides, as measured at the time of dispensing or by assessment at the time of collection. This will have a critical impact on the fit and comfort of the finished spectacles and there is absolutely no substitute for visually checking the fit of the side behind each ear. It is important to ensure the bend of each side sits snugly on the top of the ear and that the drop does not cause any pressure on the skin behind the ears. The length to bend on most sides of new frames will need to be increased or decreased to some extent in order to achieve an optimum fit. The end of the side should also be angled in a little in order to follow the contour of the head. ‘Sticky out’ sides look very unattractive.
If, after shortening a side, the length of the drop is more than 40mm, this should be cut down accordingly (nobody likes ‘earring’ sides). On metal frames with thin sides, this is done relatively easily by straightening the side, removing the plastic side tip and cutting off the required amount from the end of the side. However, do not make the mistake of shortening the side tip as well. When refitting the tip, ensure the end of the side goes to the end of the tip. The open end of the tip may need to slide over a thicker section of the side, in which case you may have to get this area of the tip fairly hot to push it fully on – but not hot enough to distort the material. However, with wider metal sides, it may be necessary to shorten the tip as well. After cutting the tip, make sure that the open end is filed smooth.
If the end of a metal side is of ‘rectangular section’ it will be a lot easier to bend if the last 50mm is briefly heated to red hot with a micro flame torch and allowed to cool naturally before refitting the side tip. If required, this ‘trick’ can also be used to remove the ‘memory’ from memory metal sides to aid adjustment.
If shortening the length to bend of a plastic side results in a long drop, the end of the side may be simply trimmed by the required amount with a pair of cutting pliers. However, you will need to shape, smooth and polish the raw cut end to ensure a neat finish and that the reinforcing strip is not protruding. A hand file and emery paper or a drill fitted with a small cylindrical grind stone and buff will be needed for this.
L is for Angle (remember your geometry)
The pantoscopic tilt or joint angles of the sides should be adjusted to ensure the front of the frame sits squarely on the face. Many patients have one ear slightly higher than the other (and will delight in telling you so). The side with the lower ear will need to be set at a steeper angle so the front is straight on the face. Ideally, the plane of the front should also be parallel to the plane of the face. The lower rims should be clear of the cheeks. On many contemporary style frames fitted with wide sides it can be very difficult to alter the joint angle, so if a patient requires greatly differing joint angles it would be beneficial at the time of dispensing to suggest a metal frame with thin sides and lugs to facilitate final adjustments.
P is for Pads
The nose pads of metal frames should be adjusted to ensure that:
(i) The frame sits at the correct height (horizontal distance between the pads).
(ii) The nasal rims of the frame are equidistant from the side of the nose and do not touch the skin.
(iii) The face of the pad is aligned precisely to the vertical and splay angles of the nose.
If (iii) is not done correctly, the weight of the spectacles will be borne on only a small area of the pad. This is frequently overlooked at the time of collection and is the most common reason for patients complaining of spectacle discomfort on the nose. Use slim, long nose pad adjusting pliers to alter the vertical and splay angles of the pads to ensure that both pads are in the optimum position. This may require several small adjustments to get it absolutely right.
To achieve maximum comfort, it may sometimes be necessary to change the manufacturer’s standard pads for larger or smaller ones or with pads of a different shape or different material. There are also some proprietary pads such as Air Pad, Vinylon, Biofeel and glass hypoallergenic which can be used if discomfort or irritation is a problem with standard pads.
Getting it right
Frame adjustment is a skill that is required by everyone in the practice who is involved with patients collecting spectacles or experiencing problems with the fit. It is something which can only be learned and perfected by hands-on experience. However, by following the four methodical stages described above, the process will in time become second nature.
Stephen Clampin is a freelance dispensing optician practicing in Essex and Suffolk.
*The Frame Aligner optical gauge makes it easy to set up a frame correctly and to see exactly what adjustments are required to achieve a symmetrical alignment of the frame and hence a good fit on the face of the patient. Scales are also provided to check head width, side lengths, optical lens centres, bifocal segment heights and progressive lens markings. For more information on this product please email scoptical@outlook.com.